Starting Cosmological Simulations from the Big Bang

TL;DR

This paper introduces a novel unified numerical approach for cosmological simulations that can start from the Big Bang, improving accuracy and consistency in modeling large-scale structure.

Contribution

The authors develop a new time integration and discreteness reduction scheme enabling direct initialization at the Big Bang and convergence with high-order perturbation theory.

Findings

Simulations can be initialized at time zero.

Achieves convergence with high-order Lagrangian perturbation theory.

Enables fast, self-consistent modeling of large-scale structure.

Abstract

The cosmic large-scale structure (LSS) provides a unique testing ground for connecting fundamental physics to astronomical observations. Modeling the LSS requires numerical $N$-body simulations or perturbative techniques that both come with distinct shortcomings. Here we present the first unified numerical approach, enabled by new time integration and discreteness reduction schemes, and demonstrate its convergence at the field level. In particular, we show that our simulations (1) can be initialized directly at time zero, and (2) can be made to agree with high-order Lagrangian perturbation theory in the fluid limit. This enables fast, self-consistent, and UV-complete forward modeling of LSS observables.